1. Technical Field
The present invention is directed generally toward a method and apparatus for reporting a posted speed limit or other traffic information to the operator of a vehicle. More specifically, the present invention is directed toward a system for determining the position of a vehicle and reporting speed limit information based on the determined position.
2. Description of Related Art
When driving a vehicle, it often happens that one forgets what the posted speed limit is on the stretch of road one is driving on. In some circumstances, a driver is unable to observe the posted speed limit because the speed limit sign is obstructed from the driver""s view. In such cases, it would be helpful if the driver were provided with a constant indication of the posted speed limit, as a display on the dashboard of an automobile, for instance.
A number of solutions to this problem have been posed in the past. For instance, U.S. Pat. No. 5,819,198 describes a system in which speed limit signs emit radio signals to indicate the speed limit, and U.S. Pat. No. 3,668,624 describes a system in which speed limit information is encoded through magnets embedded in the road. One of ordinary skill in the art will appreciate that these proposed solutions require costly modifications to existing roads and highways.
What is needed is a system for reporting speed limit information in a vehicle that works with the existing transportation infrastructure in a cost-effective way.
Accordingly, the present invention provides a method and apparatus for reporting a posted speed limit to a vehicle driver.
In one embodiment of the invention, a Global Positioning System (GPS) receiver associated with the vehicle determines the position of the vehicle and uses that position as a search key in a locally-stored database to retrieve speed limit information. The retrieved speed limit information is then reported to the driver. In an alternative embodiment of the invention, the database is located in a remote location with respect to the vehicle, and database access is performed through a wireless communication link. In another embodiment of the invention, the position and speed of the vehicle are determined by triangulating cellular telephone transmissions. In yet another embodiment of the invention, a warning display is activated if the vehicle exceeds the posted speed limit. In still another embodiment of the invention, a warning chime is played through a speaker or through the earpiece of the driver""s cellular telephone, if the vehicle exceeds the posted speed limit.